'These things are more likely to happen': Collapsing banks growing more common along North Saskatchewan, geoscientist says

A photograph of "buckles" in a Husky Energy Inc. pipeline that failed in July, spilling about 225,000 litres of heavy crude and diluent near and into the North Saskatchewan River.Husky Energy Inc. / Saskatoon

Collapsing banks and landslides are becoming more common along the North Saskatchewan River, including near the site of a Husky Energy Inc. pipeline spill that released 225,000 litres of crude in July, according to a University of Saskatchewan geoscientist.

The Calgary-based oil company said the spill area was geologically “inactive” when the pipeline was installed in 1997, but rising water tables over the last five years have created slumping problems across Saskatchewan, Grant Ferguson said.

“I think that’s been pegged as the reason for a lot of these slope instabilities, slope failures … (As) the water tables come up, the soils become weaker and these things are more likely to happen.”

The underground pipeline buckled when the “active landslide” surrounding it shifted, likely due to a “high precipitation event” overwhelming weak ground with poor drainage, Stantec Consulting Ltd. said in a report commissioned by Husky.

“The estimated movement rate (of the slope) is likely not uniform during the year but is episodic, with slower and faster rates depending on site conditions, such as precipitation,” Stantec said.

Ricardo Segovia, a hydrogeologist with the Santa Fe, New Mexico-based environmental consulting firm E-Tech International, spent much of August studying the spill. He said investigation’s conclusions were not surprising, but that “ignorance is no excuse.”

“Geotechnical integrity is still the company’s responsibility,” Segovia said in a text message. “That’s a major part of the design when the pipeline is installed … Unstable soils are actually more likely to cause problems than corroded pipes.”

Husky spokesman Mel Duvall said in an email that the company has a “comprehensive pipeline integrity management program” that includes periodic inspections, analysis and other methods.

Stantec said in its report that while monitoring of the slope where the spill took place is necessary, the size and geological makeup of the slope made “remedial stabilization measures” unfeasible.

Ferguson said while it’s impossible to mitigate every risk associated with building infrastructure near rivers, the fact that slopes along the river are “sensitive to failure” will likely lead to more comprehensive monitoring and testing.

“I think to get these things permitted these days, the slopes are going to be instrumented and monitored, and along with that you’re probably going to see more environmental monitoring.”

Despite having provided a detailed analysis of the cause of the spill, Husky’s timeline of events remains murky. The company said it detected the spill early on July 21, but has not said exactly when the pipeline failed.

Acuren Group Inc., which Husky hired to perform a metallurgical analysis of the broken pipeline, said in its report that “the timing of the original buckling of the pipe could not be determined in our investigation.”

Duvall said in an email that pressure anomalies were detected in the pipeline on July 20 — one day before the spill was identified — but that work underway on the broader pipeline network had led to similar anomalies in the past.

“The investigation concluded that the operators responded appropriately to the data being observed and took proper steps to investigate,” Duvall said in the email.

The provincial government is conducting its own investigation into the spill. It’s unclear when that will be completed, but Energy and Resources Minister Dustin Duncan said on Thursday that its preliminary findings are consistent with Husky’s investigation.

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